Structure, magnetic and dielectric properties in nano-crystalline Yb2CoMnO6

https://doi.org/10.1016/j.matchemphys.2020.122709Get rights and content

Highlights

  • Nano-crystalline Yb2CoMnO6 sample adopts monoclinic structure with P21/n phase group.

  • Paramagnetic to ferromagnetic phase transition is observed around Tc = 56 K.

  • Temperature dependent Raman study reveals spin–phonon coupling in Yb2CoMnO6.

  • Large dielectric constant and thermally activated relaxation is observed Yb2CoMnO6.

  • AC conductivity study shows quantum mechanical tunneling phenomenon.

Abstract

Structural, magnetic and dielectric properties have been studied for Yb2CoMnO6. Nano-crystalline sample of Yb2CoMnO6 synthesized by sol–gel method and structural analysis shows that the sample crystallizes in monoclinic crystal structure with P21/n phase group. To understand the charge state of Co, Mn and Yb we have performed the XPS study. Magnetic study shows that the sample undergoes a paramagnetic to ferromagnetic phase transition around Tc 56 K and an additional magnetic ordering at a lower temperature around 14 K due to ordering of Yb3+ magnetic ions. Temperature dependent Raman study reveals that spin–phonon interaction is present in this material. Further, we have studied the dielectric properties of this material. We observed that the material shows a relaxation behavior that obeys the thermally activated relaxation mechanism. Impedance spectroscopy reveals that the material shows non-Debye’s behavior. AC conductivity study is performed to understand the conduction mechanics which involve the quantum mechanical tunneling phenomenon.

Introduction

Materials which simultaneously shows ferroelectricity and magnetism are termed as multiferroic materials [1], [2]. Strong coupling of electric and magnetic properties can be utilized for vast industrial applications, for instance, storage devices, sensors, tunable microwave filters, etc. [3], [4], [5], [6]. Recently, several double perovskite materials have exhibited coupled magnetic and electric phenomenon. Among them, a new double perovskite Ba2FeMnO6 have shown co-existence of electric and magnetic hysteresis and considered as a promising candidate for spintronic applications [7]. The tunable magneto-electric effect has been observed in Y2MnCrO6 which have further intensified the quest of multiferroic materials in double perovskites [8]. Interestingly, novel high-temperature multiferroicity have been observed in a 3d-5d based Bi2(Ni/Mn)ReO6 compound [9]. Despite having an interesting physics and exotic phenomenon with promising potential for industrial applications these materials have not been well studied.

Among the vast class of compounds 3d based R2CoMnO6 (where R = rare earth elements) has received much attention of researchers due to their exotic properties such as E type ferromagnetic ordering, spin–phonon coupling, multiferroicity, magnetoelectricity, etc. In these double perovskites the spin magnetic moment of Co2+ and Mn4+ interact via dominant super-exchange interaction and give rise to ferromagnetic ordering in these materials. However, in addition to this magnetic phase transition, the rare-earth ions also interact at low temperatures and in most cases align themselves in opposite direction to the Co/Mn sublattice and thus results in an antiferromagnetically ordered state. It is worth to mention some previous findings, for instance, Lu2CoMnO6 shows E-type magnetic ordering around 50 K with an anomaly in dielectric constant at same temperature which suggests some kind of magneto-electric interplay in this material [10]. Further, this material shows pyroelectric properties and has shown negative magnetocapacitance [11]. In another case, Er2CoMnO6 shows a ferromagnetic ordering of Co and Mn cations around 67 K with a low temperature ferrimagnetic ordering around 10 K activated by Er3+ ions [12]. The pyroelectric and polarization properties of Y2CoMnO6 have been studied and confirms that no intrinsic magnetoelectric multiferroicity exists [13]. Magnetization and neutron study of single crystalline Yb2CoMnO6 shows E-type ferromagnetic ordering and also shows negative magnetocapacitance [10]. Strong magnetic anisotropy and metamagnetic transition have been observed in a self flux-grown single crystal of Yb2CoMnO6. In this study, we aim to investigate the magnetic and dielectric properties of nano-crystalline Yb2CoMnO6 and compare the results with bulk study to identify the effect of reduced dimensions.

In the present study, we report structural, magnetic, dielectric and transport properties of nano-crystalline Yb2CoMnO6. The structural analysis shows the sample is in single phase and adopts the monoclinic crystal structure with P21/n space group. Magnetization study reveals that the Yb2CoMnO6 is a ferromagnetic material that undergoes PM–FM phase transition around Tc 56 K. The material also shows antiferromagnetic ordering at low temperature. Raman study shows spin–phonon coupling is present in this material. Dielectric measurement shows a strong dispersion in dielectric constant and tangent loss shows a relaxation phenomenon. The impedance spectroscopy shows that Yb2CoMnO6 does not follow Debye’s model. The Nyquist plot analysis shows non-Debye’s behavior Yb2CoMnO6. AC conductivity shows strong frequency dependency at the higher frequency limit. The conductivity analysis shows that the conduction mechanism involves the quantum mechanical tunneling phenomenon.

Section snippets

Experimental details

Sol–gel method has been employed to synthesize the nano-crystalline Yb2CoMnO6. Starting ingredients with high purity (99.9%) from Alpha Aesar were used. First, we have prepared solutions of each compound in separate beakers. We have dissolved Mn(CH2CO2).4H2O, Co(NO3)2.6H2O and nitric acid in water with continuous stirring till the solution becomes clear. However, Yb2O3 is insoluble in water to make a clear solution we have added nitric acid drop by drop to the beaker containing Yb2O3 and water

Structural study

Fig.1a shows the X-ray diffraction pattern along with Rietveld refinement for nano-crystalline Yb2CoMnO6 double perovskite. In this figure the black open circles are experimental data, the bold red solid line is the calculated model, the blue weak line is the difference in experimental and calculated pattern. The fitting parameter goodness of fit χ2 = 1.93 which is quite reasonable. Further, from fitting we obtained Rwp/Rexp ratio 1.38 which is reasonably good and acceptable [14], [15], [16].

Conclusion

Yb2CoMnO6 nano-crystalline was successfully synthesis by sol–gel method. In the present study, we report structural, magnetic, dielectric and transport properties of nano-crystalline Yb2CoMnO6. The structural analysis shows that the sample is in single phase and adopt monoclinic crystal structure with P21/n space group. Magnetization study reveals that the Yb2CoMnO6 is a ferromagnetic material that undergoes PM–FM phase transition around Tc 56 K. The material also shows

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We acknowledge MNIT Jaipur, India for XPS data and AIRF (JNU) for magnetic measurement facilities. We acknowledge UGC-DAE-Consortium Indore and Dr. V.G. Sathe for Raman data. We also acknowledge Dr. A.K. Pramanik for dielectric measurement and UPEA-II, India funding for LCR meter. Author Ilyas Noor Bhatti acknowledges University Grants Commission, India for financial support.

Declaration of ethical responsibility

Our submission is original and has not been or is not being submitted to the peer review process to any other

References (48)

  • RaviS. et al.

    Ceram. Int.

    (2017)
  • BhattiIlyasNoor et al.

    Phys. Lett. A

    (2019)
  • SahooR.C. et al.

    J. Magn. Magn. Mater.

    (2017)
  • BhattiIlyasNoor et al.

    Physica B

    (2019)
  • BhattiIlyasNoor et al.

    Ceram. Int.

    (2020)
  • BhattiImtiazNoor et al.

    Phys. Lett. A

    (2019)
  • BhargavaS.C. et al.

    J. Magn. Magn. Mater.

    (2007)
  • PuliV.S. et al.

    Mater. Chem. Phys.

    (2016)
  • WangK.F. et al.

    Adv. Phys.

    (2009)
  • FiebigM. et al.

    Nat. Rev. Mater.

    (2016)
  • HeronJ.T. et al.

    Phys. Rev. Lett.

    (2011)
  • SeidelJ. et al.

    Nature Mater.

    (2009)
  • HoffmannT. et al.

    Phys. Rev. B

    (2011)
  • SaljeE.K.H.

    Chem. Phys. Chem.

    (2010)
  • YongF. et al.

    Chin. Phys. B

    (2014)
  • LezaiM. et al.

    Phys. Rev. B

    (2011)
  • BlascoJ. et al.

    Appl. Phys. Lett.

    (2015)
  • Yez-VilarS. et al.

    Phys. Rev. B

    (2011)
  • BanerjeeA. et al.

    Phys. Rev. B

    (2018)
  • BlascoJ. et al.

    Phys. Rev. B

    (2016)
  • BhattiImtiazNoor et al.

    Phys. Rev. B

    (2017)
  • BhattiImtiazNoor et al.

    J. Phys.: Condens. Matter

    (2014)
  • WangX. et al.

    RSC Adv.

    (2017)
  • QiuB. et al.

    RSC Adv.

    (2017)
  • Cited by (4)

    • Structure, magnetism and dielectric study of nano-crystalline Gd<inf>2</inf>CoMnO<inf>6</inf>

      2020, Solid State Sciences
      Citation Excerpt :

      The XPS spectra of these elements are fitted with XPS PEAKFIT 4.1. Fig. 2a shows the core level spectrum of Co 2p 3/2 at 796.01 eV corresponding to +2 charge state which is in agreement with reported literature [39–43]. Besides the strong Co 2p peak a small less intense satellite peak is also been observed close to Co 2p peaks (see figure).

    View full text